If ever a play exemplified the notion that a play is meant to be seen on stage and not simply read on the page, it is Nick Payne's Constellations, a captivating romantic journey across time and space. Brought vividly to life in this Underground Railway Theater production by the vision and stellar direction of Scott Edmiston, the infinite possibilities imagined by the playwright are exquisitely realized in the performances of Marianna Bassham and Nael Nacer. At all times, they are playing one couple, Marianne and Roland, but their numerous variations in response to changing circumstances bring out additional characteristics or attitudes that swell the number of people whose lives we get to observe.

Although the play tells a simple story, it is told in a complex format that challenges the audience to let go of linear thinking. On the page, Constellations is a little like Groundhog Day, with passages repeated nearly verbatim and offering very few stage directions to clarify implicit differences between them. However, put those same words in the mouths of Bassham and Nacer, and they cascade into the air in a rainbow of colorful expressions. If we didn't know that everything is carefully scripted, we might think we are watching an exceptionally good improvisation between a couple whose synchronicity is astounding. In fact, it is a two-hander master class.

Marianne and Roland meet at a party and begin to date. That's about all we know for sure, as different scenarios roll on, one after another, in which they may fall in love, may move in together, may have a nasty breakup, or may face the ultimate separation due to a terminal illness. Then again, maybe there is no illness, maybe their relationship dies with a whimper rather than a bang, or maybe they end up living happily ever after. Payne's premise is that we live in a known universe, but there could possibly be multiverses in which our lives are replicated, albeit with a panoply of different choices made by our counterparts. He explores this theory via the relationship of Marianne and Roland, teaching us a little about the science of quantum cosmology and the art of beekeeping along the way, and leaving the lingering question of whether or not anything really happens for a reason.

Edmiston's thoughtful direction and the perfectly matched performances of the actors are of a piece with the well-crafted design elements. The simple set by Susan Zeeman Rogers is a shiny, black stage with a mirrored ceiling and a clear back wall that reveals dozens of bare lightbulbs dangling at various heights and depths. Lighting designer Jeff Adelberg alters their brightness so that sometimes they appear as light bulbs, while at other times they appear as twinkling stars. At the conclusion of each scenario, there is a brief blackout, accompanied by a litany of sounds devised by Dewey Dellay. I heard a sizzling sound, like a fading firework, that I imagined to be the death of a star, and an exhalation of breath that may have been someone's last. Both actors are dressed in white and grey by costume designer Charles Schoonmaker, with Bassham's gauzy tunic top conveying an ethereal quality.

Constellations premiered at the Royal Court Theatre in January, 2012, and played on Broadway for two months in 2015 (January-March). Edmiston maintains the British flavor of the play with the actors articulating the appropriate accents, as well as employing Payne's prescribed American Sign Language in one scene. It is fascinating to discover that, even if ASL is unfamiliar, we can follow the conversation as both Bassham and Nacer make it very understandable by their facial expressions and body language. Likewise, most of us probably lack an understanding of quantum physics, but we can still accept the theory of infinite possibilities and imagine that we do not reside in the only universe. At its most basic level, Constellations is about two ordinary people who fall in love and nobody needs a Master of Science to understand that.